For years information technology has been supporting continuous advancements made by electronic industry. Therefore, it is possible for multimedia video industry to pursue their product goals such as better miniaturization technique and better portability in either research and development field or manufacturing field. As a result, it can be very convenient for a passenger when he/she is sitting in an airplane or automobile to view a multimedia LCD screen installed on the backside of headrest of a seat. As for the price of displayer, it has been largely decreased since the product manufacturers are very competitive in introducing new products with better miniaturization techniques. For this reason, it is now very common to see a displayer installed in an automobile because most people can afford it. If a displayer is installed for viewing from the front seat, the displayer can be installed on the panel of car or inset inside the panel for a pullout when needed. On the other hand, if a displayer is installed for viewing from the backseat, the displayer is usually installed on the backside of headrest of front seat. In addition, the displayer can further be installed beneath the roof panel for a flap-open view when needed.
A conventional displayer is installed on the backside of headrest. The installation method is to provide a recess at the backside of headrest and then inset a displayer in. But the drawback of this method is that viewing angle of the displayer cannot be adjusted. Therefore, a U.S. Patent Publication No. 5507556 entitled “Seat Including an Automatically Adjustable Display Screen Assembly” is disclosed for improving the drawback. This prior invention discloses a displayer screen assembly that can be viewed from automatically adjustable viewing angles. The display screen assembly is mounted on the seatback of a seat, wherein a recess is provided thereon and a frame is used for fastening the display screen assembly. Besides, a pivot bolt is used for fastening the display screen assembly to the frame as well as allowing pivoting movement of display screen assembly relative to the seatback. Also, the frame is further connected to a mechanism of seatback movement by a control rod. Therefore, the viewing angles of display screen assembly can be automatically adjusted in accordance with the upright or reclined position of the seat.
However, automobile crash testing has proved that traditional fastening method for a displayer is pretty dangerous because the displayer might be detached from the seatback when a car accident occurs, and the detached displayer might hit passengers sitting in the backseat, causing injuries to the passengers. Therefore, in consideration of safe ride for passengers, the dismounting job on a mounting apparatus of displayer is intentionally designed to be difficult so as to ensure installation safety in an automobile.
Moreover, although the prior art allows viewing angles of a displayer to be automatically adjustable according to upright or reclined position of backseat, the manufacturing cost and maintenance cost of displayer will have to be increased because the displayer is complicated-designed to comply with the mechanism of seatback movement.
In conclusion, drawbacks of a conventional mounting apparatus can be listed as below:                (1) The possible location for installing a conventional displayer in an automobile is at the panel of front seat, the headrest of backseat, or the roof panel. Unfortunately, there is no such mounting apparatus that can be universally applied to displayers installed in different locations; in other words, different mounting apparatuses have to be designed in accordance with different locations of displayer. To illustrate, if a displayer is to be inset inside a headrest for inset installation, a protruded axle or concaved point must be provided at two sides of the frame of mounting apparatus so that the protruded axle or concaved point can be corresponding to relative concaved hole or protruded axle located at the base of mounting apparatus for positioning. Therefore, the displayer can be firmly mounted and viewed from adjustable angles. On the other hand, if a displayer is to be externally installed on the panel, the positioning method is to allow the backside of the frame to be joined to a supporting rack for positioning. From the above description, it proves that the mounting method for inset installation is different from that of external installation. Therefore, it is necessary to design two different modules for manufacturing the mounting apparatus. For this reason, cost of production will become very high.        (2) As mentioned above, there must be a protruded axle or a concaved point provided at two sides of the displayer frame to position an inset-in displayer. If, another mounting structure is directly provided at the backside of frame for external installation, the protruded axle or concaved point at two sides of frame will then be located at the outer side of frame, which will spoil aesthetic value of the displayer.        (3) To ensure more stable positioning effect, the degree of difficulty for dismounting the mounting apparatus of displayer has to be increased. Therefore, a maintenance worker who does the dismounting job will have to pay more effort and strength during the dismounting process. The improper strength, however, might cause the protruded axle for positioning to break off or cause damage to it.        